Comparison of transposed brachiobasilic fistulas to upper arm grafts and brachiocephalic fistulas.

BACKGROUND: Renewed interest in transposed brachiobasilic fistulas has occurred since the release of the National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-DOQI) guidelines because it is an alternative method to achieve an upper arm fistula in patients who cannot achieve a functional brachiocephalic fistula. The objective of this study was to compare outcomes among transposed brachiobasilic fistulas, upper arm grafts, and brachiocephalic fistulas. METHODS: A cohort of patients with upper arm accesses was retrospectively identified. Access outcomes were determined from medical records and contact with physicians, dialysis providers, and patients. Primary outcome was thrombosis-free survival. Secondary outcomes were primary failure, time to use, risk of catheter-related bacteremia, need for intervention, incidence of access-related complications, cumulative, and functional patency. Group differences in age, sex, race, diabetes, peripheral vascular disease, and number of previous accesses were adjusted for in the analysis where appropriate. RESULTS: Transposed brachiobasilic fistulas, upper arm grafts, and brachiocephalic fistulas were compared in 59, 82, and 56 patients, respectively. Compared with transposed brachiobasilic fistulas, upper arm grafts were more likely to thrombose with an adjusted relative risk (RR) of 2.6 (95% CI, 1.3 to 5.3) excluding primary failures and 1.6 (95% CI, 1.0 to 2.7) when accounting for the lower risk of primary failure for grafts. Transposed brachiobasilic fistulas also required less intervention (0.7 vs. 2.4 per access-year, P < 0.01) and were less likely to become infected (0 vs. 13%, P < 0.05) than grafts. Mature brachiocephalic fistulas were less likely to fail (RR 0.3, 95% CI, 0.1 to 1.0) and showed a trend for less thrombosis (RR 0.3, 0.1 to 1.1) than mature brachiobasilic fistulas. There was no significant difference in cumulative patency (failure-free survival) among the three types of access if primary failure was included at the median follow-up of 594 days. Transposed brachiobasilic fistulas provided catheter-free access one month sooner than brachiocephalic fistulas and one month later than upper arm grafts. CONCLUSIONS: Transposed brachiobasilic fistulas provide cumulative patency equivalent to upper arm grafts and brachiocephalic fistulas. They are less likely to thrombose and become infected than upper arm grafts. Compared with brachiocephalic fistula, they are more likely to mature but are at increased risk of thrombosis after maturation. Transposed brachiobasilic fistulas should be considered before placing an upper arm graft for patients that cannot achieve a functional brachiocephalic fistula.

Acute hemodynamic changes during carotid artery stenting.

To determine the clinical significance of acute hemodynamic disturbances during stenting in the carotid sinus region, we assessed the relation between intraprocedural changes in heart rate (HR) and blood pressure (BP) and adverse neurologic and cardiac outcomes. Eighteen patients underwent carotid stenting with the Wallstent (Schneider Inc). Suitable candidates had at least 60% diameter stenosis of the carotid artery by angiography. Initial and nadir HR and BP were recorded during the predilatation, stent delivery, and postdilatation periods. Bradycardia was defined as HR < or =60 beats/min and hypotension as systolic BP < or =100 mm Hg. Nineteen Wallstents were successfully deployed in all 19 carotid arteries. Some degree of bradycardia or hypotension occurred in 68% of carotid stent procedures, but administration of vasoactive medications was necessary in only 7 patients (37%) with more persistent hemodynamic disturbances. Hypotension or the need for continuous vasopressor therapy was significantly more common during postdilatation (32%) than in the predilatation period (5%) (p = 0.02). Bradycardia was not reduced by prophylactic atropine. In 1 patient the hemodynamic response to stenting may have contributed to an adverse neurologic and cardiac outcome. Thus, despite frequent fluctuations in HR and BP, most carotid stenting procedures were performed with excellent overall results, even in patients at high risk.

Measurement of vascular input impedance in infrainguinal vein grafts.

The purpose of this investigation was to measure vascular input impedance in infrainguinal vein grafts and assess the importance of clinical and hemodynamic parameters in predicting graft patency. Fifty-seven patients undergoing infrainguinal vein bypass grafting for limb salvage (n = 40) or claudication (n = 17) were prospectively studied. At the time of revascularization, simultaneously acquired intraluminal pressure and blood flow waveforms were digitized at 200 Hz and subjected to Fourier transformation in near real-time. Input impedance was calculated at baseline (immediately after unclamping) and after stimulation with either papaverine or completion arteriography. Resistance (Rin) was calculated as mean pressure divided by mean blood flow (Q). Characteristic impedance (Z0) was calculated as the mean of harmonics 3-10. Intraoperative data acquisition required approximately 5 min, utilized the completion angiography cannula already in place, and was uncomplicated in all patients. Stimulation with either papaverine or arteriography resulted in increased Q (72 +/- 7 to 146 +/- 11 ml/min, p < 0.001), decreased Rin (126 +/- 13 to 52 +/- 4 x 10(3) dyne.s.cm-5, p < 0.001), and slightly decreased Z0 (18 +/- 2 to 15 +/- 1, p = 0.002). After a mean follow-up of 20 months, the 2-year primary patency, secondary patency, limb salvage, and survival rates were 61 +/- 8%, 74 +/- 7%, 76 +/- 6%, and 86 +/- 6%, respectively. Primary patency was not associated with any of the clinical variables studied including age, sex, smoking history, history of previous vascular surgery, hypertension, coronary artery disease, diabetes mellitus, creatinine, indication for revascularization (claudication versus limb salvage), anesthesia (general versus regional), or level of distal anastomosis (popliteal versus infrapopliteal). Furthermore, there was no association between primary patency and baseline Q, baseline Rin, or stimulated Z0. However, using univariate analysis, patency was positively associated with decreased stimulated Rin (p = 0.002), elevated stimulated Q (p = 0.006), and decreased baseline Z0 (p = 0.02). Multiple regression analysis identified stimulated Rin as the only independent predictor of primary patency (p = 0.002). Stimulated Rin > or = 50 x 10(3) dyne.s.cm-5 was 71% sensitive and 65% specific for graft failure. It is concluded that 1) vascular input impedance can be simply and reliably measured in the operating room, and 2) elevated stimulated Rin is an independent predictor of primary patency.

Axillary grafts for difficult hemodialysis access.

PURPOSE: This study describes the largest reported experience to date with axillary artery-to-axillary vein or axillary artery-to-jugular vein polytetrafluoroethylene bridge fistulas for hemodialysis access. The purpose of the study was to determine the incidence of complications and the durability of the access to better determine the role of this procedure in the dialysis access algorithm. METHODS: A single center's experience over a period of 5 years was retrospectively reviewed. RESULTS: Twenty-six axillary grafts were placed in 24 patients. All but one were used for dialysis. At the time of access creation, the patients had been undergoing dialysis for a mean of 77 months (range, 5 to 256 months), had had a mean of 9.4 previous access procedures, and had exhausted all arm sites. The life-table patency rate at 3 years was 60%. The incidence of infection and thrombosis were comparable with conventional arm bridge fistulas. Neither vascular steal phenomenon nor neurologic injury occurred in this series. CONCLUSIONS: Axillary artery-to-axillary vein or axillary artery-to-jugular vein polytetrafluoroethylene bridge fistula is an excellent and durable secondary access strategy. We recommend that it be used after exhaustion of conventional arm sites.

Effects of pulsatile perfusion on human saphenous vein vasoreactivity: a preliminary report.

This study examined the effects of exposure to arterial blood pressure and flow on human saphenous vein catecholamine sensitivity. Unused portions of saphenous vein from eight patients undergoing peripheral bypass procedures were mounted parallel in a specially designed organ culture apparatus and perfused with tissue culture medium with 95% CO(2) at 37 degrees C. One segment was fixed between two cannulas while the medium was gently agitated (control) and the other was actively perfused via a pulsatile pump system at a rate of 60 beats/min, peak pressure of 100 mmHg and peak flow of 200 ml/min (pulsed; mean pressure 60 mmHg; mean flow 115 ml/min). After 48 h, vein segments were removed and tested for in vitro isometric contraction in response to KCI, norepinephrine and histamine, and relaxation in response to acetylcholine, calcium ionophore A23187, and sodium nitroprusside. There were no differences in mean(s.e.m.) maximal contraction in response to KCI (control 0.61(0.16) g versus pulsed 0.72(0.27)g; P = n.s.), norepinephrine (control 1.00(0.56) g versus pulsed 1.51(0.54) g; P= n.s.), or histamine (control 1.47(0.85) g versus pulsed 1.95(0.64) g; P= n.s.). However, pulsed veins exhibited increased sensitivity to both norepinephrine (control -logED50 6.20(0.23) versus pulsed mean(s.e.m.) 6.60(0.17); P< 0.05) and histamine (control -logED(50) 5.60(0.27) versus pulsed 6.24(0.20); P = 0.05). Pulsed veins exhibited slightly less acetylcholine-induced relaxation although the difference did not reach statistical significance (control mean(s.e.m.) relaxation at 1 x 10(6)M 9.2(14.0)% versus pulsed -13.3(6.4)%; P = n.s.). There were no differences in relaxation in response to either A23187 (control 1 x 10-(4)M 178(19)% versus pulsed 191(68)% or sodium nitroprusside (control 225(15)% versus pulsed 254(17)%; P = n.s.). The data presented herein indicate that exposure of human saphenous vein to the hemodynamics of the arterial environment for 48 h results in catecholamine supersensitivity while contractile and relaxant function are not affected.

A comparison of amrinone with sodium nitroprusside for control of hemodynamics during infrarenal abdominal aortic surgery.

OBJECTIVES: The control of hemodynamic changes during surgical resection of abdominal aortic aneurysms (AAA) remains a challenge to anesthesiologists. In the past, hypertensive episodes have been treated with sodium nitroprusside (SNP). However, amrinone may provide some benefits when compared with SNP because of its positive inotropic and vasodilatory properties. Therefore, the purpose of this study was to compare amrinone with SNP for hemodynamic control during AAA surgery. DESIGN: This study was a prospective, randomized investigation. SETTING: This study was performed at a single university hospital. PARTICIPANTS: This study included 20 patients undergoing AAA resection. INTERVENTIONS: After institutional review board approval, participants were randomized to receive either SNP (group N = 10) or amrinone (group A = 10). Both agents were started 10 minutes before aortic cross-clamping and discontinued 10 minutes before unclamping. Anesthesia was induced with thiopental or etomidate and maintained with oxygen, nitrous oxide, isoflurane, fentanyl, and vecuronium. Hemodynamic measurements included heart rate, systolic and diastolic blood pressure, cardiac output, systolic and diastolic pulmonary artery pressure, pulmonary capillary wedge pressure, central venous pressure, mixed venous oxygen saturation, electrocardiogram, and ST-T wave trend analysis. MEASUREMENTS AND MAIN RESULTS: Demographic and clinical characteristics for the two groups were similar. Mixed venous oxygen saturation was significantly lower (p < 0.05) in group N immediately after unclamping. There were no differences between groups for the other measurements studied. There were no episodes of myocardial ischemia in either group. CONCLUSIONS: This study demonstrates that amrinone provides equivalent hemodynamic control to SNP during abdominal aortic aneurysm surgery because it allows moderate reductions in blood pressure without affecting other hemodynamic measurements. Further studies are needed to assess whether patients with poor preoperative left ventricular function would benefit from amrinone management during AAA resection.

Ultrasonographically guided manual compression of femoral artery injuries.

To determine the success and complication rates of ultrasonographically guided manual compression in patients with femoral arterial injuries after femoral arterial catheterization, we performed 53 sonographically guided compression repairs in 51 patients. Ultrasonographically guided compression repair was performed on 40 pseudoaneurysms in non-anticoagulated patients, seven pseudoaneurysms in anticoagulated patients, four arteriovenous fistulas on non-anticoagulated patients, and one pseudoaneurysm combined with an arteriovenous fistula. One pseudoaneurysm underwent two separate ultrasonographically guided compression repairs: once when the patient was anticoagulated and once after anticoagulants were withheld. Ultrasonographically guided compression repair was successful in 37 of 48 pseudoaneurysms (77%). Of the 40 pseudoaneurysms in non-anticoagulated patients, ultrasonographically guided compression repair was successful in 36 (90%). This repair technique failed in all seven pseudoaneurysms in anticoagulated patients. Ultrasonographically guided compression repair was successful in 13 of 16 (81%) multilobulated pseudoaneurysms but failed in all arteriovenous fistulas and the one case of pseudoaneurysm combined with an arteriovenous fistula. Ultrasonographically guided compression repair is a safe and effective alternative to surgery for the repair of pseudoaneurysms, including multilobulated pseudoaneurysms. The procedure does not appear to be effective in the anticoagulated patient or in patients with an arteriovenous fistula.

Revascularization of the internal mammary artery after coronary artery bypass grafting.

Symptomatic anterior myocardial ischemia as a result of stenosis at the origin of the left internal mammary artery developed in a patient who underwent prior coronary artery bypass grafting using the left internal mammary artery as a conduit. Successful revascularization of the left anterior descending coronary artery was achieved using a reversed saphenous vein bypass graft from the left common carotid artery to the proximal internal mammary artery. This approach provided myocardial revascularization and avoided reoperative median sternotomy.

Asymptomatic carotid artery stenosis and stroke in patients undergoing cardiopulmonary bypass.

PURPOSE: This study was undertaken to assess the natural history of carotid artery stenosis in patients undergoing cardiopulmonary bypass (CPB) at a Veterans Administration Medical Center. METHODS: Between January 1989 and August 1993, all patients undergoing CPB were offered preoperative carotid artery ultrasound screening as part of an investigative protocol. Patients were monitored in-hospital for the occurrence of perioperative neurologic deficit. RESULTS: A total of 582 patients underwent carotid artery ultrasound screening. Greater than 50% stenosis or occlusion of one or both internal carotid arteries was present in 130 patients (22%), with 80% or greater stenosis or occlusion of one or both arteries present in 70 patients (12%). In-hospital stroke or death occurred in 12 (2.1%) and 36 (6.2%) patients, respectively. Of the 12 strokes, five were global and seven were hemispheric in distribution. Of the five patients who had global events, none had evidence of carotid artery stenosis. However, of the seven patients who had hemispheric events, five had significant 50% or greater stenosis or occlusion of the internal carotid artery ipsilateral to the hemispheric stroke. Therefore the presence of carotid artery stenosis or occlusion was significantly associated with hemispheric stroke (no stenosis 0.34% vs stenosis 3.8%; p = 0.0072). Furthermore, the risk of hemispheric stroke in patients with unilateral 80% to 99% stenosis, bilateral 50% to 99% stenosis, or unilateral occlusion with contralateral 50% or greater stenosis was 5.3% (4 of 75). No strokes occurred in patients with unilateral 50% to 79% stenosis (n = 52). CONCLUSIONS: It is concluded that carotid atherosclerosis is a risk factor for hemispheric stroke in patients undergoing CPB.

Surgical management of carotid artery atherosclerotic disease.

Cerebrovascular disease remains an important cause of disability and death in the geriatric population. This paper reviews the current state of knowledge with respect to the pathogenesis and medical and surgical treatment of carotid atherosclerosis. The majority of strokes are probably due to embolization from an ulcerated atherosclerotic plaque at the carotid bifurcation rather than from ischemia produced by global reduction in cerebral blood flow related to obstruction of the carotid arteries. Ultrasonography is an appropriate screening examination, but most vascular surgeons consider contrast angiography to be essential in the preoperative evaluation. Large clinical trials have evaluated the efficacy of stroke prevention by carotid endarterectomy in symptomatic patients. The North American Symptomatic Carotid Endarterectomy Trial clearly demonstrated a benefit of surgery in stroke prevention as compared with optimal medical therapy after only 18 months of follow-up. The European Carotid Surgery Trial and a VA Cooperative Study produced similar conclusions. Much less information is available concerning the patient with carotid atherosclerosis who has no cerebral symptoms. No convincing evidence that surgery is beneficial has yet been demonstrated, but a large multicenter clinical trial (Asymptomatic Carotid Atherosclerosis Study) remains in progress.

Vascular complications of the intra-aortic balloon pump: an analysis of 436 patients.

Although the intra-aortic balloon pump can be a lifesaving device, vascular complications are often associated with its use. Four hundred thirty-six patients underwent insertion of a balloon pump over a 14-year period. Indications for the balloon pump were intraoperative pump failure (42%), unstable angina (24%), preoperative prophylaxis (22%), preoperative shock (9%), and postoperative support (3%). Placement of the intra-aortic balloon pump was by percutaneous insertion in 66 per cent of patients, the remainder were placed by direct exposure of the vessel. Vascular complications occurred in 46 (10.6%) patients. Limb ischemia was seen in 40 of 46 of these patients. Other complications included bleeding in three patients, dissection in two patients, and infection in one patient. The effects on morbidity of sex, diabetes, site of cardiac catheterization, duration of counterpulsation, and the presence or absence of pulses on admission were determined. Only the absence of pedal pulses on admission correlated with an increased incidence of vascular complications (P = 0.04). Twenty four per cent of those with complications were diabetics, compared with 16 per cent of patients who received balloon pumps but had no complications. Surgical interventions in the ischemic limbs consisted of thrombectomy alone (28 of 40) or thrombectomy and vascular bypass (5 of 40). Four femorofemoral crossover grafts and one saphenous vein interposition graft were used. Five limbs were lost to amputation, or 1 per cent of the entire group.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of abdominal aortic graft complications.

OBJECTIVE: This study reviews the outcome of 61 patients who underwent 66 reoperations for complications of aortic grafts. There were 25 patients with false aneurysm of an aortic anastomosis and 41 patients with graft infection, 17 of whom had involvement of the gastrointestinal tract. SUMMARY BACKGROUND DATA: Significant late complications of aortic grafting occurred in 2% of patients. The mode of clinical presentation, the clinical characteristics, and outcome in these patients has not been emphasized. METHODS: This study reviews our experience with patients with complications of aortic grafts requiring graft excision or replacement with a view towards identifying prominent and important clinical characteristics and predictors of successful treatment. CONCLUSIONS: Patients with involvement of the gastrointestinal tract have higher mortality and morbidity than patients with simple aortic graft infection or those who require aortic graft replacement for pseudoaneurysm formation at the aortic anastomosis. These patients require longer hospitalization, more blood transfusion, and have higher operative and long-term mortality. Revascularization of the lower extremities should be attempted and has a high rate of limb salvage although revision or thrombectomy may be required. The authors recommend complete graft excision and extra-anatomic bypass for patients with aortic graft infections.

Reduction of experimental vein graft intimal hyperplasia by ketanserin.

Intimal hyperplasia is considered to be the result of smooth muscle cell proliferation. Experimental vein grafts (VG) in the rabbit develop intimal hyperplasia and a contractile response to serotonin (5-HT), mediated by a 5-HT2 receptor. 5-HT is known to stimulate smooth muscle cell proliferation in vitro and therefore may be linked to the development of intimal hyperplasia. This study examines the effect of a 5-HT2 antagonist, ketanserin (KT) on vein graft morphology and function at 14 and 28 days after grafting. Forty-three New Zealand White rabbits underwent common carotid interposition bypass grafting. Twenty-two were treated with KT (0.86 mg/kg/day po) 5 days prior to surgery and thereafter until harvest. The remaining 21 animals acted as controls. VG were harvested at 14 (VG14) and 28 (VG28) days for histology or vasoreactivity. Twenty-three VG were harvested by pressure fixation and the midportions of the grafts were examined by videomorphometry. Standard isometric tension studies in response to serotonin and norepinephrine (NE) were performed on the rings from the remaining 20 VG. Contralateral external jugular veins (CV) from both groups were studied to assess the functional toxicity of KT. There were no toxic effects to KT noted. KT therapy did not affect the functional activity of the CV at 14 or 28 days when compared to controls. When compared to controls, KT significantly reduced the intimal thickness (49 +/- 11 vs 113 +/- 24 microns; P = 0.04) and there was an increase in luminal area (16.89 +/- 2.13 vs 8.41 +/- 1.59 mm2; P < 0.02) in VG28 only.(ABSTRACT TRUNCATED AT 400 WORDS)

Hypercholesterolemia and experimental vein grafts: accelerated development of intimal hyperplasia and an increase in abnormal vasomotor function.

Hypercholesterolemia is an important risk factor for the development of atherosclerosis. Late vein graft failure has been attributed to a combination of both intimal hyperplasia and atherosclerosis. This study examines the effect of hypercholesterolemia on the early morphology and vasomotor function of experimental vein grafts. Forty New Zealand White rabbits received either a 1% cholesterol diet (n = 24; HC) or a standard diet (n = 16; CON) for 4 weeks before operation and thereafter until harvest. All animals underwent a reversed vein common carotid artery bypass. The vein grafts and contralateral veins were harvested at 2 and 4 weeks after operation in both groups for either histological and morphometric analysis (n = 8 for each group) or for in vitro isometric tension studies using serotonin (5-HT), norepinephrine (NE), bradykinin (BK), and endothelin-1 (ET) and following NE precontraction, relaxation in response to acetylcholine (ACh) and sodium nitroprusside (SNP). Serum cholesterol levels were measured after 4, 6, and 8 weeks of the cholesterol diet. Serum cholesterol concentrations were 20 to 30 times higher than controls in the hypercholesterolemic animals at all times. The intimal area of the grafts in the HC group increased by twofold at 2 weeks and threefold at 4 weeks compared to corresponding controls. In contrast to the CON vein grafts, the intima of the vein grafts from HC consisted mainly of lipid-laden smooth muscle cells with scattered interspersed macrophages and occasional lipid plaques between the intima and the media. Medial areas were similar in all grafts. HC grafts became progressively more sensitive to 5-HT at 2 and 4 weeks. A supersensitivity to NE and BK developed at 4 weeks in HC grafts. There was no change in sensitivity to ET. While no graft relaxed to ACh, HC grafts contracted at low doses. All grafts responded to SNP in a dose-dependent manner. In contrast to CON veins, HC veins demonstrated an increase in sensitivity to NE and a contractile response to 5-HT (at 4 weeks only). HC veins did not relax in a dose-dependent manner in response to ACh. No changes in the morphology of HC veins were noted. HC produces changes in the structure and associated vasomotor abnormalities of vein grafts. Closely related functional changes also occur in contralateral veins. HC appears to induce intrinsic changes in smooth muscle cells which are linked to a greater proliferative and abnormal vasomotor capability. Clinically, applications of vigorous anti-HC regimens perioperatively may be beneficial in maintaining patency over the longer term.

Computer-assisted modeling of blood-flow: theoretical evidence for the existence of optimal flow wave patterns.

The purpose of this study was to model blood-flow waveforms in order to examine the relationship between various waveform shapes and input impedance spectra. Twenty distinct single cardiac cycle flow waveforms having the same mean flow and heart rate were created based on clinical and published observations. The "best" waveform was one with a steep flow upstroke, a high peak flow value, swift deceleration following peak flow, and flow reversal during diastole. Each flow waveform was paired with 20 computer-generated pressure waveforms to calculate input impedance spectra by discrete Fourier transformation. "Favorable" flow waveforms were associated consistently with a lower characteristic impedance (average of 4th-10th harmonics, Zav) irrespective of the shape or magnitude of the input pressure wave. Zav corresponds to the degree of compliance of the vascular bed and could be expected to be lower under favorable outflow conditions and in non-diseased vessels. In conclusion, this study provides theoretical evidence for the existence of optimal flow wave patterns and supports the notion of flow waveform assessment for diagnostic purposes.

Appearance of oxidized cellulose (Surgicel) on postoperative CT scans: similarity to postoperative abscess.

OBJECTIVE: Oxidized regenerated cellulose (Surgicel), a sterile knitted fabric that causes thrombus formation because of its physical properties, is frequently used for intraoperative hemostasis. Unlike traditional surgical sponges, it is bioabsorbable and can be left in the surgical bed. On CT scans, the appearance of the retained oxidized cellulose can mimic that of an abscess. The purpose of this study was to describe the appearance of oxidized regenerated cellulose on postoperative CT scans so that an erroneous diagnosis of an abscess can be avoided. MATERIALS AND METHODS: We reviewed the CT examinations of five postoperative patients in whom oxidized regenerated cellulose had been used for surgical hemostasis. Operative reports and surgeons confirmed the use of oxidized cellulose. Four CT scans were abdominal examinations, and one was a head examination. RESULTS: In four cases, CT scans showed focal, linear collections of gas within masses with mixed attenuation in or near the operative site. No air-fluid levels were present. In three patients, cultures of specimens obtained by aspiration were negative for pyogenic organisms. CONCLUSION: Retained oxidized cellulose can mimic an abscess on CT scans. Focal collections of air centrally located within a mass should alert the radiologist that oxidized cellulose may have been placed in the operative site, and an appropriate history should be sought.

Saphenous vein endothelium-dependent relaxation in patients with peripheral vascular disease.

In vitro vasomotor responses of saphenous veins of 15 patients undergoing peripheral vascular bypass procedures were studied. Vessels were harvested by standard techniques, sectioned into 4 mm rings, and suspended in organ baths under isometric tension. Stimulation with cumulative doses of norepinephrine revealed a -logED50 of 6.85 +/- 0.12 M and maximal tension of 8.64 +/- 1.77 g. Patient characteristics suggesting high maximal response (by univariate analysis) included male sex (male 11.69 +/- 2.49 g versus female 5.08 +/- 1.69 g; p = 0.058). Intact and denuded rings were additionally tested for endothelium-dependent relaxation following submaximal norepinephrine precontraction. The vessels relaxed in response to acetylcholine (maximal relaxation 31.1 +/- 10.7% at 1 x 10(-6) M), calcium ionophore A23187 (85.3 +/- 11.8% at 1 x 10(-5) M), and sodium nitroprusside (150.8 +/- 15.2% at 1 x 10(-5) M), but only acetylcholine relaxation was completely endothelium-dependent. Calcium ionophore A23187 relaxation was partially dependent on the endothelium while sodium nitroprusside relaxation was entirely endothelium-independent. Negligible relaxation was observed in response to adenosine diphosphate (ADP) (12.1 +/- 12.8% at 1 x 10(-5) M) while histamine and serotonin caused additional contraction only. We concluded that, in patients undergoing vascular surgical procedures, the saphenous vein (1) demonstrates variable contractile function which appears to be greater in males following spinal anesthesia, and (2) exhibits moderate endothelium-dependent relaxation in response to acetylcholine and calcium ionophore A23187 but not to ADP, histamine, or serotonin.

Parenteral anticoagulation with the heparinoid Lomoparan (Org 10172) in patients with heparin induced thrombocytopenia and thrombosis.

Progressive thrombocytopenia may develop in as many as 5% of patients receiving heparin anticoagulation. In these patients, the risk of thromboembolic complications as well as continued thrombocytopenia necessitates discontinuation of heparin and initiation of an alternative anticoagulant when indicated. The heparinoid Lomoparan (Org 10172) is a mixture of several non-heparin low molecular weight glycosaminoglycans with proven anticoagulant efficacy that is generally non-reactive with platelets in the presence of plasma from patients with heparin induced thrombocytopenia, whereas standard heparin will induce platelet aggregation. We evaluated the role of heparinoid as a potential alternative anticoagulant in patients with heparin induced thrombocytopenia. During a 6 month period, we identified six patients with heparin induced thrombocytopenia who required an alternative parenteral anticoagulant, four as primary treatment for specific medical problem, and two as anticoagulation during a necessary surgical procedure. Heparinoid was used successfully in both medical and surgical patients requiring parenteral anticoagulation. In no case was there an exacerbation of the thrombocytopenia nor thromboembolic complications while on heparinoid therapy. Three of our patients sustained hemorrhagic complications, predominantly in the post-surgical setting in association with elevated anti-factor Xa levels and additional anticoagulant agents. We feel that these results confirm the utility of heparinoid anticoagulation in a select subset of patients with heparin induced thrombocytopenia who require continued parenteral anticoagulation.